Region of birth, sex, and agricultural work of immigrant Latino farm workers: the MICASA study.

Agricultural work is hazardous, and immigrant workers perform the majority of production tasks, yet there are few data describing agricultural work and use of protective measures by demographic characteristics. We examined cross-sectionally the influence of region of birth (Mexico vs. Central America) and sex on agricultural work and use of protective measures in the MICASA cohort of immigrant Latino farm workers in Mendota, California. Of 445 participants, 293 (65.8%) were born in Mexico (163 men, 130 women) and 152 (34.2%) were born in Central America (80 men, 72 women). Men worked on average 74.4 more days than women (95% CI 62.0, 86.9) and were more likely to perform tasks requiring high levels of training or strength, such as machine operation, pruning, picking, planting, and irrigation; more likely to work in dusty conditions; and more likely to work directly with pesticides. Women predominated in packing. Respondents from Mexico were more likely to work with tomatoes and less likely to work with melon and lettuce. Central America-born respondents were less likely to engage in planting, irrigation, and pesticide use. Use of task-appropriate personal protective measures on at least a half-time basis was rare, with the exception of persons working with pesticides (a group limited to men) and for facial scarves among Central American women. Further work should focus on identifying barriers to use of preventive measures and programs to further their use. Educational models accounting for cultural factors and driving social norm change, employer engagement, and use of community health workers (promotores) may be helpful in promoting use of preventive measures.

Factors associated with agricultural work performed by adolescents from an immigrant farm worker population (MICASA study).

UNLABELLED: While studies have looked at the relationship of adolescent employment with health outcomes and risk behaviors, few have focused on children of hired farm workers. These children face unique challenges affecting their health and work environment. Exploring the frequency and nature of agricultural work characteristics among adolescent children of Hispanic hired farm workers is important for assessing the potential risks they face. METHODS: MICASA is a population-based study of settled immigrant Hispanic farm working families in Mendota, California. We selected a cross-sectional random sample of adolescents (ages 11 to 18). Interviews assessed work history, place of birth, and acculturation. RESULTS: 38% of participants were female and 62% were male; 55% were born in the U.S., 38% in Mexico, and 7% in El Salvador; and 49% worked for pay during the last year. Among those who worked, farm work was most frequently reported (73.5%). Among those who had done farm work, the mean age at initiation was 14 years, and they worked a mean of 4.3 weeks during the previous year. Hoeing, picking, and packing/sorting were the most common tasks. In models adjusted for age and sex, low-acculturated adolescents were more likely than moderately acculturated to have worked in the past 12 months, to start work younger than age 14 years, and to do farm work. SIGNIFICANCE: Farm work is common among adolescents in this Hispanic agricultural community and is strongly associated with foreign birth and low acculturation.

Engaging a hard-to-reach population in research: sampling and recruitment of hired farm workers in the MICASA study.

Hired farm workers provide the majority of the workforce for California's labor-intensive agricultural sector Agriculture is one of the most hazardous occupations, but there has been little research into the etiology of poor health outcomes that occur disproportionately in hired farm worker populations. MICASA is a cohort investigation of occupational and environmental health risks in hired farm worker households in Mendota, California, that employed a two-stage sampling process, including random selection of census blocks and door-to-door enumeration. The aim of this analysis was to evaluate the success of the sampling process and compare demographics of the enumerated population to other regional samples of Latino populations. In the enumeration, 1257 addresses were mapped and 729 hired farm worker households were enumerated. Findings showed no significant differences between the enumerated population and the resulting MICASA study sample; however, the MICASA population was more likely to be male, from Central America, work in agriculture, and have fewer years residency in the U.S. than California Health Interview Survey (CHIS) respondents. Additionally, 9.4% of the enumerated dwellings were back houses or unofficial dwellings and may have been missed by the U.S. Census 2000. Demographic comparisons between the enumerated population, census data, and CHIS data highlight the differences in these sampling methods and suggest possible demographic changes in hired farm workers in California. While difficulties in accessing hired farm workers often account for the lack of population-based research, the MICASA cohort provides an opportunity to examine occupational health patterns relevant to other farm worker populations.

Protection against breathing dust: behavior over time in Californian farmers.

The aim of this study was to determine whether Californian farmers changed respiratory protective behaviors over time and the personal characteristics associated with protective behaviors. We surveyed 588 farmers longitudinally from 1993 to 2004. Questions included frequency of protective mask or respirator use in dusty conditions and the percentage of time the farmers drove a tractor with a closed cab. To assess longitudinal associations between protective behaviors and potential covariates, general estimating equation modeling was used with adjustment for subject age, study date, and other covariates. Only 25% of the farmers were "very" concerned about respiratory risks. Over time, any use of a dust mask or respirator decreased significantly, from 54% in 1993 to 37% in 2004 (p-value < or = 0.0001), while consistent use of respiratory protection was maintained by 20% of the cohort. Use of a closed-cab tractor increased slightly from 14% in 1993 to 17% in 2004 (p-value = 0.04). Farmers who were ex-smokers and those concerned about respiratory risk were more likely to consistently use a dust mask or respirator. However, the more acreage or time spent in dust, the less likely farmers were to use protection. Closed-cab tractor use was associated with higher salary, more time driving tractors, and larger acreage farmed. Emission reduction remains a priority. Exposure reduction by closed-cab tractor use was not associated with perception of respiratory risk. As mask or respirator use was most positively associated with respiratory concern, more effort needs to be concentrated on educating farmers about long-term respiratory health risks, and providing more user-friendly personal protective equipment.

Application of an enzyme-linked immunosorbent assay for the analysis of paraquat in human-exposure samples.

Paraquat is a toxic quaternary ammonium compound used as an herbicide around the world. Easy, fast, and inexpensive but sensitive methods are needed to study the effects of long-term, low-level exposure of paraquat on human health. An enzyme-linked immunosorbent assay (ELISA) was used for quantification of paraquat in urine and air-filter samples collected in a human-exposure study among farm workers in Costa Rica. A sample pretreatment consisted of removal of interfering substances using solid-phase extraction resin columns. The precision and accuracy of the method were tested using duplicate spiked urine samples. The correlation between results for blind samples obtained using ELISA and liquid chromatography-mass spectrometry was significant (R2 = 0.945 and 0.906 for spiked and field samples, respectively). With an LOQ of 2 ng mL(-1), this ELISA method was able to distinguish the exposed from the nonexposed farm workers. For the air-filter analysis, paraquat was extracted by 9 M H2SO4 at 60 degrees C for 12 hours, and the results obtained by ELISA showed good correlation (R2 = 0.918) with the spectrophotometric (256 nm) measurements. Paraquat in acid-stabilized urine samples was very stable, and no significant losses were detected during a 3-month storage at room temperature, at 4 degrees C, or at -20 degrees C.

Nonfatal occupational injury among California farm operators.

We conducted a population-based telephone survey addressing farm-work-related (FWR) injuries among California farm operators. Of 1947 participants (80.4% response), 135 farm operators reported 160 FWR injuries in the preceding year, yielding a one-year cumulative incidence for any FWR injury of 6.9% (95% CI 5.8%-8.2%), or a mean 8.2 FWR injuries per 100 farmers in the preceding year (95% CI 6.8-9.7). Multiple injury events in the same individual occurred more frequently than predicted by chance. Sprains and strains (29.4%) were the most frequently reported injury and predominantly involved the back. Overexertion represented the most frequent external cause (24.2%), followed by machinery (14.3%), falls (13.0%), and animals (12.4%). Factors associated with FWR injury included white ethnicity (OR 3.19; 95% CI 1.38-7.36), increased annual hours worked on the farm, low levels of administrative work, and increased percentage of time working with livestock. FWR injury experience of California farm operators is comparable with that reported for other agricultural populations. Above-expected frequency of multiple injuries supports involvement of personal or environmental risk factors. Preventive efforts should focus on higher-risk groups and preventing overexertion and muscle strain and injury related to machinery, falls, and animals, especially livestock.

Current health effects of agricultural work: respiratory disease, cancer, reproductive effects, musculoskeletal injuries, and pesticide-related illnesses.

Agriculture has experienced major bio-technological advances and economic and socio-cultural disruptions since the publication of "Agriculture at Risk" in 1988. At that time, it was recognized that there were acute needs in the prevention of musculoskeletal syndromes and injuries, agricultural respiratory disease, noise-induced hearing loss, pesticide-related illnesses, and concerns regarding the excesses of cancers noted in epidemiological studies of farmers. In this article, we discuss the progress made in identification of new respiratory syndromes related to confined animal feeding operations, pesticide-related illnesses, cancers implicating agricultural exposures, and ergonomics in agriculture. The focus is on the current state of knowledge in these areas, the author's recommendations for further improvement in research techniques, and the potential application of this information to improve human health in production agriculture nationwide.

Self-reported hand dermatitis in California veterinarians.

BACKGROUND: Veterinarians are exposed to allergens, dirt, and chemicals, but there are very few epidemiologic data on dermatoses veterinarians. OBJECTIVE: The aim of this study is to get information about skin diseases in veterinary work. METHODS: A sample of California veterinarians were sent a questionnaire, which was returned by 73% (n = 1,416). RESULTS: History of skin atopy was reported by 11% and respiratory atopy by 63%. Dermatoses during their career were reported by 46%, and hand and/or forearm dermatitis was reported more than once and during the past year by 22% of women and 10% of men. Dermatitis with work-related exacerbating factors was reported by 28%. Almost 1 of 5 veterinarians reported animal-related skin symptoms. Other aggravators were medications (2%), gloves (4%), and other chemicals (7% of respondents). Of those with animal-related dermatitis, 65% reported only 1 animal (dog, 66%; cat, 29%; horse, 9%; and cattle, 8%), and 66% reported the symptoms appeared in minutes after the contact. In logistic analysis, the risk factors for the appearance of hand/forearm dermatitis during the past 12 months and more than once during their career, were: history of skin atopy (odds ratio, 3.5), childhood hand dermatitis (odds ratio, 3.4), history of respiratory atopy (odds ratio, 2.0), and female sex (odds ratio, 1.9). CONCLUSIONS: Veterinarians' skin symptoms were common and often caused by immediate allergy to 1 or few animal species.

Costs of occupational injuries in agriculture.

OBJECTIVE: This study was conducted to estimate the costs of job-related injuries in agriculture in the United States for 1992. METHODS: The authors reviewed data from national surveys to assess the incidence of fatal and non-fatal farm injuries. Numerical adjustments were made for weaknesses in the most reliable data sets. For example, the Bureau of Labor Statistics (BLS) Annual Survey estimate of non-fatal injuries is adjusted upward by a factor of 4.7 to reflect the BLS undercount of farm injuries. To assess costs, the authors used the human capital method that allocates costs to direct categories such as medical expenses, as well as indirect categories such as lost earnings, lost home production, and lost fringe benefits. Cost data were drawn from the Health Care Financing Administration and the National Council on Compensation Insurance. RESULTS: Eight hundred forty-one (841) deaths and 512,539 non-fatal injuries are estimated for 1992. The non-fatal injuries include 281,896 that led to at least one full day of work loss. Agricultural occupational injuries cost an estimated $4.57 billion (range $3.14 billion to $13.99 billion) in 1992. On a per person basis, farming contributes roughly 30% more than the national average to occupational injury costs. Direct costs are estimated to be $1.66 billion and indirect costs, $2.93 billion. CONCLUSIONS: The costs of farm injuries are on a par with the costs of hepatitis C. This high cost is in sharp contrast to the limited public attention and economic resources devoted to prevention and amelioration of farm injuries. Agricultural occupational injuries are an underappreciated contributor to the overall national burden of health and medical costs.

Distribution of particulate matter and tissue remodeling in the human lung.

We examined the relationship between intrapulmonary particle distribution of carbonaceous and mineral dusts and remodeling of the airways along anatomically distinct airway paths in the lungs of Hispanic males from the central valley of California. Lung autopsy specimens from the Fresno County Coroner's Office were prepared by intratracheal instillation of 2% glutaraldehyde at 30 cm H(2)O pressure. Two distinct airway paths into the apico-posterior and apico-anterior portions of the left upper lung lobe were followed. Tissue samples for histologic analysis were generally taken from the intrapulmonary second, fourth, sixth, and ninth airway generations. Parenchymal tissues beyond the 12th airway generation of each airway path were also analyzed. There was little evidence of visible particle accumulation in the larger conducting airways (generations 2-6), except in bronchial-associated lymphoid tissues and within peribronchial connective tissue. In contrast, terminal and respiratory bronchioles arising from each pathway revealed varying degrees of wall thickening and remodeling. Walls with marked thickening contained moderate to heavy amounts of carbonaceous and mineral dusts. Wall thickening was associated with increases in collagen and interstitial inflammatory cells, including dust-laden macrophages. These changes were significantly greater in first-generation respiratory bronchioles compared to second- and third-generation respiratory bronchioles. These findings suggest that accumulation of carbonaceous and mineral dust in the lungs is significantly affected by lung anatomy with the greatest retention in centers of lung acini. Furthermore, there is significant remodeling of this transitional zone in humans exposed to ambient particulate matter.

Environmental asbestos exposure and mesothelioma.

Epidemiologic studies of mesothelioma have focused primarily on occupational exposures to asbestos. Nonoccupational exposure to asbestos can be grouped into three main categories: paraoccupational (familial), neighborhood, and true environmental exposures. Elevated mesothelioma rates not attributable to occupational exposures have been observed in asbestos mining and manufacturing areas. Asbestos is one of the most dangerous environmental carcinogens because of the small dose known to cause mesothelioma and the rapid lethality of the disease once it develops. Further research is needed to characterize the contribution and risk profile for environmental asbestos and mesothelioma, and for the development of public health policy.

Personal fluoride and solvent exposures, and their determinants, in semiconductor manufacturing.

Personal air sampling for fluorides and solvents was done at 35 semiconductor fabrication facilities in the United States. Fluoride compounds were used in etching and cleaning operations, and solvents were used in photoresist and developing operations. All personal solvent and fluoride levels were less than 2 percent of current Occupational Safety and Health Administration (OSHA) standards. Statistical models of the exposure determinants for the target agents found production level, as indicated by number of semiconductor wafer cassettes loaded/unloaded from the target machines or baths, was predictive of fluoride, xylene and 1-methoxy-2-propyl acetate exposures. The percent of fresh air ventilation and the percent of xylene in the photoresist were also significant determinants in the statistical model predicting personal xylene exposure levels.

Personal exposure to dust, endotoxin and crystalline silica in California agriculture.

AIMS: The aim of this study was to measure personal exposure to dust, endotoxin and crystalline silica during various agricultural operations in California over a period of one year. METHODS: Ten farms were randomly selected in Yolo and Solano counties and workers were invited to wear personal sampling equipment to measure inhalable and respirable dust levels during various operations. The samples were analysed for endotoxin using the Limulus Amebocyte Lysate assay and crystalline silica content using X-ray diffraction. In total 142 inhalable samples and 144 respirable samples were collected. RESULTS: The measurements showed considerable difference in exposure levels between various operations, in particular for the inhalable fraction of the dust and the endotoxin. Machine harvesting of tree crops (Geometric mean (GM) = 45.1 mg/m3) and vegetables (GM = 7.9 mg/m3), and cleaning of poultry houses (GM = 6.7 mg/m3) showed the highest inhalable dust levels. Cleaning of poultry houses also showed the highest inhalable endotoxin levels (GM = 1861 EU/m3). Respirable dust levels were generally low, except for machine harvesting of tree crops (GM = 2.8 mg/m3) and vegetables (GM = 0.9 mg/m3). Respirable endotoxin levels were also low. For the inhalable dust fraction, levels were reduced considerably when an enclosed cabin was present. The percentage of crystalline silica was overall higher in the respirable dust samples than the inhalable dust samples. CONCLUSIONS: Considerable differences exist in personal exposure levels to dust, endotoxin and crystalline silica during various agricultural operations in California agriculture with some operations showing very high levels.

Determinants of personal dust exposure during field crop operations in California agriculture.

The aim of this study was to identify determinants, if any, of personal dust exposure levels during agricultural field crop operations in California. Personal dust concentrations were measured with four-stage cascade impactors and respirable dust cyclones. Altogether, 57 cascade impactor measurements and 63 cyclone measurements were used for analyses. High personal dust concentrations were measured during most operations, in particular during ground preparation operations such as land planing and discing. For the larger dust particles, which is dust collected on all stages of the cascade impactor and dust with a 50% cutoff < 9.8 microns, the most important determinants of personal dust exposure were the presence of an enclosed cabin, relative humidity, type of operation, and tractor speed. The presence of an enclosed cabin on the tractor, higher relative humidity, and lower tractor speed were all associated with a decrease in personal dust levels. For smaller dust particles, which is dust with a 50% cutoff < 3.5-4 microns, the presence of an enclosed cabin, relative humidity, and soil temperature appear to be related to dust levels. The results of this study could be used to reduce the high levels of personal dust exposure currently experienced by those who work in field crop farming in California.

Exposure to dust and its particle size distribution in California agriculture.

The aim of this study was to measure personal dust exposure levels and the dust particle size distribution during various agricultural operations in California. Personal dust exposure levels were measured with four-stage cascade impactors and respirable dust cyclones during field crop, fruit and nut farming, and dairy operations at three farms. Altogether, 103 cascade impactor measurements and 108 cyclone measurements were taken. High personal dust exposure levels were measured during various operations in particular during ground preparation operations such as land planing (geometric mean [GM] = 57.3 mg/m3, geometric standard deviation [GSD] = 2.4) and discing (GM = 98.6 mg/m3, GSD = 2.9). Dust particles were relatively large and the great majority belonged to the extrathoracic fraction. Dust levels were considerably lower when an enclosed cabin was present on the tractor; for example, during discing, dust exposure levels were reduced more than sixtyfold for the larger dust particle fraction and more than fourfold for the respirable dust fraction.

The relation between subjective dust exposure estimates and quantitative dust exposure measurements in California agriculture.

Measuring exposure levels for epidemiologic research is time consuming and expensive and therefore subjective exposure estimates are sometimes used instead. In this study we related the subjective dust exposure estimates of workers in California agriculture to personal dust exposure measurements. One hundred and twenty-four observations were available for comparison of subjective dust estimates and inhalable dust measurements and 129 observations for comparison of subjective dust estimates and respirable dust measurements. Individual subjective dust estimates showed weak to moderate correlations with measured dust concentrations for both the inhalable (Rs = 0.67) and respirable dust fraction (Rs = 0.36). The within-worker reliability coefficients were low (0.2 and 0.1, respectively). Grouped subjective dust estimates performed better and showed a consistent increase with average measured dust levels, in particular for the inhalable dust fraction (R2 = 0.81). Age, the number of years working in agriculture, education level, the presence of any respiratory symptoms, and the language of the questionnaire did not have a significant independent effect on the relationship between measured dust levels and subjective dust estimates. California agricultural workers appear to be reasonably good at estimating inhalable dust levels, in particular if an average of many different workers is taken, but they are unable to provide good estimates of respirable dust levels. Measuring dust levels remains the preferred option.

Self-reported stress and reproductive health of female lawyers.

We studied the prevalence and relationship of stress and working conditions with adverse reproductive outcomes in a cohort of female US law-school alumnae. A total of 584 female lawyers (74% response), aged 25 to 63, responded to a mailed questionnaire. Job hours per week was a strong predictor of job stress. In a logistic regression analysis, women working > 45 hours/week were five times as likely to report high stress as those working < 35 hours/week. Marriage and length of time on the job showed a small inverse association with stress. Women who worked more than 45 hours/week during their first trimester of pregnancy were more likely to report high stress at work during pregnancy. After being adjusted for confounding factors, weekly job hours during the first trimester of pregnancy showed a strong independent association with spontaneous abortion risk (odds ratio [OR], 3.0; 95% confidence interval [CI], 1.4 to 6.6). Seven or more alcohol drinks/week was also independently associated with spontaneous abortion risk (OR, 4.8; 95% CI, 1.5 to 18.1). Self-reported stress during pregnancy was positively but not statistically significantly associated with spontaneous abortion (OR, 1.4; 95% CI 0.8 to 2.3).

Risk factors for systemic illnesses following agricultural exposures to restricted organophosphates in California, 1984-1988.

Organophosphate (OP)-related systemic illnesses reported to the Worker Health and Safety (WH&S) Branch, and restricted OP-related agricultural use data reported to the Information Services Branch at the California Department of Food and Agriculture (CDFA) (now CAL-EPA) during 1984-1988 were used to assess factors associated with OP-related systemic illnesses. Counts of OP-related systemic illnesses (numerator), relative to OP-related use data (denominator), such as pounds applied, number of applications, and acres treated (pounds applied/acres treated), were analyzed by crop treated, season of application, method of application, geographic region, and by specific OP applied. A Relative Illness/Use Ratio (RIUR) was calculated by Poisson regression. The highest risk of systemic illness was associated with OP applications to fleshy fruit (mainly fruit trees) compared to all other crops combined (RIUR = 2.9, 95%CI = 2.2-3.9) using pounds applied in the denominator, followed by vegetables and melons (RIUR = 1.9, 95%CI = 1.4-2.4). Air applications resulted in higher RIURs for systemic illness than did ground applications (RIUR = 2.1, 95%CI = 1.7-2.5). Specific OPs that showed significantly elevated RIURs for systemic illness when compared to other OPs were Mevinphos (RIUR = 5.8, 95%CI = 5.0-6.8), Demeton (RIUR = 4.3, 95%CI = 2.6-7.1), Oxydemeton-Methyl (RIUR = 3.8, 95%CI = 3.0-4.9), Methamidophos (RIUR = 1.6, 95%CI = 1.2-2.0) and Azinphos-Methyl (RIUR = 1.3, 95% CI = 1.1-1.6).

Occupationally induced airways obstruction.

The studies reviewed in this article indicate the association of occupational exposure to a variety of organic and inorganic dusts and various gases and fumes with chronic bronchitis and decrements of FEV1. Usually an obstructive pattern was noted, although in some occupations a similar decrement in FVC was noted. The effect of smoking on chronic bronchitis, respiratory symptoms, and FEV1 was usually additive, although workers exposed to cotton dust in one study demonstrated an interaction between exposure and smoking, as did a study of a general population sample. In coal workers, exposure to dust in younger workers resulted in a greater decline in lung function than if the exposure occurred in older workers. Studies in coal miners and grain workers further suggest that occupational standards in effect are not sufficient to protect the working population from adverse effects. The magnitude of the effect of occupation on decrement in FEV1 is usually less than cigarette smoking. Studies in coal miners indicate, however, that a minority of workers could be more severely affected by exposure. When considered together with cigarette smoking, additional decrements in lung function because of occupational exposure could contribute to disability. Additional study is needed for better understanding of exposure-response relationships, host factors, potential interaction with cigarette smoking, and pathophysiology of the development of occupationally induced airway disease.